The core advantage of quantum computing -- the ability to compute for many
possible outcomes at the same time and therefore crunch data much more quickly
than classical computers -- also creates a problem for data security. Once the
first high-powered quantum computers are functioning, they'll be able to quickly
saw through many of our most common data encryption algorithms. But as it turns
out, an obscure encryption code created in 1978 is
resistant to all known methods of quantum attack.

Hang Dinh at the University of Connecticut and a few colleagues figured out
that CalTech mathematician Robert McEliece's code is structured in such a way
that a quantum computer couldn't just pull it apart, at least not by any known
process. Rooted in a mathematical puzzle called the hidden subgroup problem,
standard quantum fourier analysis simply can't crack the code.

What does all that mean? For a more extensive mathematical explanation, click
through to Tech
Review's more thorough and astute review of quantum encryption. But in
summary, encryption is often conducted using asymmetric codes, meaning there's a
public key that anyone can use to encrypt data and a private key for decrypting
it. The basis of these encryption schemes is math that flows easily in one
direction but not so easily in the other.

Such asymmetric code can be tricky for a classical computer to figure out but
quantum computers are well suited to such work. To take a simple example, say a
message was encrypted using basic multiplication -- one number is multiplied by
a number to get a third number. It's not so easy to look at the third number and
quickly determine the two numbers that spawned it.